Inflammatory bowel disease (IBD), which occurs world-wide and afflicts millions of people, is the collective term used to describe three gastrointestinal disorders of unknown etiology: Crohn's disease (CD), ulcerative colitis (UC), and indeterminate colitis (IC). IBD, together with irritable bowel syndrome (IBS), will affect one-half of all Americans during their lifetime, at a cost of greater than $2.6 billion dollars for IBD and greater than $8 billion dollars for IBS. A primary determinant of these high medical costs is the difficulty of diagnosing digestive diseases and how these diseases will progress. The cost of IBD and IBS is compounded by lost productivity, with people suffering from these disorders missing at least 8 more days of work annually than the national average.
Despite the successes of anti-TNFα therapies in the treatment of IBD, a subpopulation of patients are refractory to treatment, highlighting an unmet medical need for new therapies. Vedolizumab is a gut-specific, α4β7 integrin-neutralizing monoclonal antibody, which does not affect peripheral blood cell counts and appears to lack systemic effects. Vedolizumab is a new anti-inflammatory treatment option for the management of therapy-refractory patients. In addition, ustekinumab is a IL12p40 monoclonal antibody, which is another novel IBD therapeutic. However, the availability of diagnostic tests to accurately measure the levels of biologics such as vedolizumab and ustekinumab is necessary for the effective use of these novel therapeutics in IBD patients.
As such, there is a need in the art for assays to detect the presence or level of biologics such as vedolizumab and ustekinumab in a patient sample to monitor drug therapy and to guide treatment decisions. Such assays are particularly useful for the therapeutic management of diseases such as ulcerative colitis and Crohn's disease using an individualized approach to monitor drug efficacy and optimize therapy accordingly, and can include assessing disease course and clinical parameters such as pharmacodynamics, disease activity indices, disease burden, and inflammatory biomarkers. The present invention satisfies this need and provides related advantages as well.